Fly.io runs your app on servers around the world, close to your users. It's great for global teams and offers competitive pricing with a generous free tier.

Why Fly.io?

• Global edge deployment
• Built-in Redis (Upstash integration)
• Generous free tier (3 shared VMs)
• Simple CLI-based deployment
• Automatic SSL and load balancing

Prerequisites

• A GitHub account
• Fly.io account (sign up at fly.io)
• Fly CLI installed (brew install flyctl or see fly.io/docs/hands-on/install-flyctl)
• MongoDB Atlas account for database

Step 1: Set Up MongoDB Atlas

1. Create a free cluster at mongodb.com/atlas
2. Set up a database user and note the password
3. In Network Access, allow connections from 0.0.0.0/0
4. Get your connection string from Connect → Connect your application

Step 2: Initialize Fly.io App

Navigate to your Maillayer directory and run:

fly auth login
fly launch

When prompted:

• Choose an app name (e.g., maillayer-production)
• Select a region close to you
• Say No to setting up a PostgreSQL database
• Say No to setting up an Upstash Redis (we'll add it separately)
• Say Yes to deploy now? No (we need to configure first)

Step 3: Create Upstash Redis on Fly

Fly.io has native Upstash Redis integration:

fly redis create

Select:

• A name like maillayer-redis
• The same region as your app
• Choose Free plan for testing or a paid plan for production

Copy the Redis URL from the output.

Step 4: Configure Secrets

Set your environment variables as secrets:

fly secrets set NODE_ENV=production
fly secrets set BASE_URL=https://maillayer-production.fly.dev
fly secrets set NEXTAUTH_SECRET=your-secret-key-minimum-32-characters
fly secrets set TRACKING_SECRET=your-tracking-secret
fly secrets set MONGODB_URI="mongodb+srv://user:pass@cluster.mongodb.net/maillayer"
fly secrets set REDIS_URL="redis://default:password@your-redis.upstash.io:6379"

Step 5: Configure fly.toml

Your fly.toml should look like this:

app = "maillayer-production"
primary_region = "ord"

[build]
  dockerfile = "Dockerfile"

[http_service]
  internal_port = 3000
  force_https = true
  auto_stop_machines = false
  auto_start_machines = true
  min_machines_running = 1

[[vm]]
  cpu_kind = "shared"
  cpus = 1
  memory_mb = 512

Important: Set auto_stop_machines = false to keep workers running.

Step 6: Deploy

fly deploy

Wait 3-5 minutes for the build and deployment. Access your app at https://your-app.fly.dev.

Step 7: Add Custom Domain (Optional)

fly certs add mail.yourdomain.com

Follow the DNS instructions provided, then update your BASE_URL:

fly secrets set BASE_URL=https://mail.yourdomain.com

Monitoring & Logs

View real-time logs:

fly logs

Monitor your app:

fly status
fly dashboard

Scaling

Scale memory for high-volume email processing:

fly scale memory 1024

Add more instances:

fly scale count 2

Estimated Costs

Total: Free to start, ~$15-25/month for production.

Troubleshooting

App keeps stopping

• Ensure auto_stop_machines = false in fly.toml for worker processes.

Build runs out of memory

• Use a larger builder: fly deploy --build-remote

Redis connection refused

• Verify the Redis URL includes the password. Check with fly redis status.

MongoDB connection timeout

• Ensure MongoDB Atlas allows connections from all IPs (0.0.0.0/0).